Radial magnetic field reduction to improve critical current of HTS solenoid

To enhance the critical current of superconducting coil, the magnetic field experienced by superconductor strand (tape) in a coil should be minimized. This is true for both low T_c and high T_c superconductors, and the difference between the two lies in their isotropic/anisotropic characteristics. In this paper, we propose a shape optimization algorithm to reduce radial magnetic field components in HTS solenoid to enhance critical current of a solenoid. In the algorithm, the finite element method and the continuum shape design sensitivity formula were employed. The objective function is to minimize the maximum radial magnetic fields in a solenoid with a constraint of constant solenoid volume condition. In this paper, the details on algorithm are introduced and the calculated optimized shapes are presented.